To prevent accumulation of material on the inner walls of pipelines, various cleaning methods have been developed. One conventional method uses mechanical scrapers, which are propelled down the length of pipe via compressed air. Alternative approaches use a variety of pressurized propellants, such as water, plastic, steel grit, ice, soda, or carbon dioxide, to scrub the inner surfaces.
In recent years, increasing efforts have been made to use pipe cleaning methods that minimize adverse environmental effects. For example, governmental regulations prevent the use of chemicals that have undesired environmental impact.
Several Russian patents teach the cleaning of pipelines with electrohydraulic transducers. The transducer is placed within a fluid-filed pipeline and energized to produce acoustic waves, which agitate the fluid and the material accumulated on the inner walls of the pipeline. These Russian patents are: SU 1315037, entitled "Pipes Inner Surface Cleaning--By Forming Equal Impact Wave Simultaneously on Pipe Opposite Sides", SU 777394, entitled "Hydraulic Pipeline Inner Surface Cleaning--Using High Voltage Transformer Connected to Impeller", and SU 404410, entitled "Boiler Pipe Cleaning--Using Hydraulic Effect.